Speirs, Mike,  1956- <br/><br/>
Indigenous integrated farming systems in the Sahel / 
Mike Speirs and Ole Olsen. 
 - Washington, D.C. :  World Bank,  c1992. 
 - x, 80 p. :  ill. ;  28 cm. 
 - World Bank technical paper,  Africa Technical Department series  no. 179.  0253-749 ; .